There exists an image forming apparatus capable of performing duplex printing. When this image forming apparatus performs duplex printing, it firstly forms an image on the front surface of a sheet, next reverses the front/back of the sheet, and then forms an image on the back surface of the sheet.
The image forming apparatus has an openable/closable side cover for eliminating a jam, when sheet clogging (jam) has occurred in the apparatus. When the jam has occurred, a user opens this side cover, removes the jammed sheet from the apparatus, and then closes the side cover.
When the user closes the side cover, an impact sound of some sort is generated. In addition, as the material for the side cover, a hard material such as a hard polycarbonate material is used for keeping the strength of the side cover. But when a hard material is used as the material of the side cover, the stiffness of the side cover is increased, and when the above-described impact sound is generated, the resonance frequency thereof becomes high. By this means, the sound quality of the impact sound when the user has closed the side cover becomes high-pitch, and thereby the user feels uncomfortable.
In addition, in order to keep the strength of the side cover, a large number of large and small ribs are arranged on the inner side surface (a surface at the inner side of the image forming apparatus) of the side cover, and thereby the side cover is reinforced. However, when the ribs are arranged, since an area of each of the ribs is small, a wavelength of the vibration to be propagated in the relevant rib becomes short, and thereby the above-described resonance frequency becomes high. By this means, the sound quality of an impact sound generated when the user has closed the side cover becomes high, and accordingly the user feels uncomfortable.
There is a case in which ventilation openings are disposed on the upper surface of the side cover, in order to release heat from the upper portion of the side cover when the side cover is in the closed state. When the openings like these are disposed, since the strength of the side cover becomes weak, countermeasure for keeping the strength such as providing the above-described rib is required, but the countermeasure for keeping the strength becomes a factor for making the sound quality of the impact sound high-pitched.
The high-itched sound quality like this makes the user feel uncomfortable, and in addition, there may be a case in which a user is made to feel that the quality of the material of the image forming apparatus is not so good and the structure thereof is rough and lacking in elegance.